Numford
Electronic configuration

Gold (Au)

[Xe] 4f¹⁴ 5d¹⁰ 6s¹, an exception. 1 unpaired electron, period 6, group 11, d block.

Element or ion

Type a symbol, a name or an atomic number, add a charge such as Fe3+ or Cl-, or tap an element in the table. Orbitals fill from m = −l up, spin +½ first.

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H1He2Li3Be4B5C6N7O8F9Ne10Na11Mg12Al13Si14P15S16Cl17Ar18K19Ca20Sc21Ti22V23Cr24Mn25Fe26Co27Ni28Cu29Zn30Ga31Ge32As33Se34Br35Kr36Rb37Sr38Y39Zr40Nb41Mo42Tc43Ru44Rh45Pd46Ag47Cd48In49Sn50Sb51Te52I53Xe54Cs55Ba56Hf72Ta73W74Re75Os76Ir77Pt78Au79Hg80Tl81Pb82Bi83Po84At85Rn86

AuGold, Z = 79, 196.967 u

[Xe] 4f14 5d10 6s1

In full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s¹

[Xe]4f5d6s
  • Blockd block
  • Period6
  • Group11
  • Valence11
  • Unpaired1
  • MagneticPara

Last electron 5d

  • n5shell
  • l2d subshell
  • m+2orbital
  • s−½spin down
Why Au is an exception

Plain filling would give [Xe] 4f¹⁴ 5d⁹ 6s². A completely filled d subshell (d¹⁰) is extra stable, for the same reasons of symmetry and exchange energy. So one s electron moves into d.

Working

Step by step

  1. Gold has 79 electrons.
  2. Fill in (n + l) order: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁹.
  3. That gives [Xe] 4f¹⁴ 5d⁹ 6s², but the accepted configuration is [Xe] 4f¹⁴ 5d¹⁰ 6s¹. A completely filled d subshell (d¹⁰) is extra stable, for the same reasons of symmetry and exchange energy. So one s electron moves into d.
  4. Write the subshells in order of n: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s¹.
  5. Replace the xenon core with [Xe]: [Xe] 4f¹⁴ 5d¹⁰ 6s¹.
At a glance

Gold (Au): the numbers

Atomic number79
Atomic mass196.967 u
Period6
Group11
Blockd block
Valence electrons11
Unpaired electrons1
Magneticparamagnetic
Last electron5d: n = 5, l = 2, m = +2, s = −1/2
Questions

Gold (Au): quick answers

What is the electronic configuration of gold?

Gold has 79 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s¹, or [Xe] 4f¹⁴ 5d¹⁰ 6s¹ in short.

Why is gold [Xe] 4f¹⁴ 5d¹⁰ 6s¹ and not [Xe] 4f¹⁴ 5d⁹ 6s²?

A completely filled d subshell (d¹⁰) is extra stable, for the same reasons of symmetry and exchange energy. So one s electron moves into d.

What are the quantum numbers of the last electron of gold?

The last electron goes into 5d: n = 5, l = 2, m = +2, s = −1/2. Orbitals fill from m = −l up, spin +½ first.

Try any element or ion